None.
Not Applicable.
This invention relates to gimbal systems, and more particularly, to a stabilized common gimbal (SCG) for use on commercial vehicles and on military vehicles employed in battlefield environments. The SCG of the present invention is usable with a variety of sensor suites such as are used on different military vehicles and is particularly advantageous over a conventional manual adjustment gimbal systems in that the remote operation of the SGC does not unduly expose a vehicle crew to danger in combat situations by requiring a crew member to exit the vehicle to perform manual adjustments.
Heretofore, gimbal systems have been built for use either with a particular set of sensors, or for use on a specific vehicle. Accordingly, it is currently impossible to use a gimbal system interchangeably on a variety of vehicles, or to swap out one sensor or set of sensors with another. This has obvious ramifications when it comes to the amount of inventory necessary to cover possible operational contingencies, the amount of training required for service personnel having to install and maintain a variety of different systems, as well as for vehicle personnel who need to know and understand the nuances of each gimbal system they may be required to use.
With regard to gimbal systems employed on combat vehicles, such vehicles, by their nature, are expected to operate over a wide variety of terrain and move through numerous positions as they traverse a battlefield. Modem military vehicles are equipped with a variety of sensors enabling them to locate and identify other forces moving over the same terrain. To properly function, it is desirable that the platform on which these sensors are mounted remain inertially stable regardless of the vehicle""s gyrations. Heretofore, maintaining a stable platform has required manual operations performed by the crew. Since the crew is subject to the same lurching as the vehicle and is exposed to enemy fire, their ability to manually maintain a stable platform has not always been optimum. In addition, the crew""s activities in trying to stabilize the sensor platform has exposed the crew to substantial risk. Accordingly, there is a need for a common gimbal system which automatically provides a stable platform for a variety of sensors, and which reduces the risk to the crew from exposure to enemy fire.
Briefly stated, the present invention provides a stabilized common gimbal. The term xe2x80x9ccommonxe2x80x9d is used because the same stabilized gimbal system can be installed on a wide variety of commercial vehicles and military vehicles, the latter of which are employed in combat situations. It is a feature of the present invention that the SCG is interchangeably usable with a wide variety of sensors or sensor packages or sensor suites and that the SCG regardless of the sensors installed on it can automatically stabilize a sensor package to a particular line-of-sight (LOS).
The SCG of the present invention is a two axis (azimuth and elevation) gimbal capable of stabilizing a payload of primary sensors weighing nominally one hundred pounds (45.5 kg) to an average positional accuracy of 25 xcexcrad. The SCG further is capable of mounting a secondary sensor payload of nominally fifty pounds (22.7 kg) that is independent of the moving axes of the gimbal. The primary and secondary sensor payloads are environmentally protected. The SCG employs three gyroscopes which are respectively used to detect inertial rates in the azimuth axis, the elevation axis, and the roll axis. The inertial rate information provided by the gyroscopes is utilized by a gimbal control during slewing of a sensor payload and its stabilization. Even though there is no controlled roll axis in the two axis system provided, the roll gyroscope is used for decoupling the azimuth and elevational axes. Further, the roll gyroscope assists in an automatic calibration procedure that reduces mechanical design tolerances, making a Gyroscope Assembly Unit (GAU) of the SCG more economical to produce.
The SCG provides an interface for a primary suite of sensors comprising one or more sensors having a common line-of-sight (LOS) and which are stabilized in both azimuth and elevation. An inertial navigation system (INS) provides navigation and measures the LOS for the primary suite of sensors relative to inertial space. An Axis Control Unit (ACU) is provided which incorporates hardware and software that provides motor drives, an interface for gimbal motion sensors, an interface to system communications, and control loop closure. The SCG provides electronics, actuators, resolvers, and inertial sensors for stabilizing the LOS of the primary suite of sensors against vehicle motion or other disturbances (e.g. wind loads). Remote positioning of the LOS of sensors in the primary suite is also accomplished. The remote commands can originate from an operator""s Common Control Panel (CCP) joystick or from commands over the system""s serial interface. System serial interface commands may originate from a tracker in the local system or from commands over any appropriate communication link, such as a radio. The SCG further provides an interface for a secondary suite of sensors again comprising one or more sensors. This second suite of sensors is not stabilized and has a base platform independent from the primary suite of sensors. Finally, the SCG includes an inherent capability for boresighting the sensors comprising the primary suite of sensors, and for retaining the boresight thereafter. The SCG has a signature which is minimized in the visible, radio-frequency (RF), and infrared (IR) portions of the spectrum.
The foregoing and other objects, features, and advantages of the invention as well as presently preferred embodiments thereof will become more apparent from the reading of the following description in connection with the accompanying drawings.